1. Field of the Invention
The present invention relates to a device and a method of optical alignment between an optical fiber and an optoelectronic semiconductor device, of the laser type for example. The device and the method are original in that they use polar coordinates rather than Cartesian coordinates to position the fiber.
2. Description of the Prior Art
It is known that, owing to the very small size of light-emitting or light-receiving optoelectronic components such as lasers, photodiodes and electroluminescent diodes, the adjusting of the alignment of the optical diodes is a delicate task since, in certain cases, it calls for precision of the order of one micrometer or even greater precision. This is why this adjusting of the alignment is very generally done dynamically and the optical fiber, which is shifted with a micromanipulator, is adjusted positionally while the optoelectronic device is in operation.
This adjusting is done along three orthogonal axes in space which, for convenience's sake, shall be called the axes Ox and Oy in a plane perpendicular to the optical axis, and the axis Oz in a plane parallel to the optical axis: the adjusting is therefore done in a system of Cartesian coordinates.
From the practical point of view, there are essentially two ways of aligning an optical fiber and an optoelectronic device. The first way is to shift the fiber inside a drop of glue or molten solder, placed in the vicinity of the light-emitting or light-receiving surface. When the optimum coupling is achieved, the drop of glue is polymerized by a flash of ultraviolet light, or the drop of solder is congealed by cooling. The method is simple and economical, but has the drawback wherein the contraction that occurs upon the hardening of the drop shifts or breaks the fiber.
The second method is based on the shifting of the fiber in two orthogonal planes, one of which is perpendicular to the optical axis while the other is parallel to the same axis. This means that the planes have to be perfectly machined so that the positioning of the fiber is precise and reliable. Furthermore, it is not always easy to fix one plane part to another plane part, except by their common edges.